A) Field of the Invention
The present invention relates to an optical disc recording method and apparatus for recording information in an optical disc such as a compact disc-recordable (CD-R), a compact disc-rewritable (CD-RW), a compact disc-write once (CD-WO), a mini disc (MD) and a digital versatile disc (DVD), and to an optical disc to be used by such a disc recording apparatus, and more particularly to an optical disc recording method and apparatus capable of detecting a proper recording velocity and the fastest recording velocity, and to a disc to be used by such a disc recording apparatus.
B) Description of the Related Art
With the spread of media such as CD-R and CD-RW and recent advances in manufacture technologies, these media are becoming very inexpensive and have the main trends in storage media. With the advent of DVD, technologies of laser used for pickup elements and recording/reproducing technologies have advanced greatly. Some optical disc recording/reproducing apparatuses can be used in the range from a low velocity (1×) to a high velocity (8×, 16×, etc.).
Optimum power control (OPC) is performed in advance to obtain an optimum power in order to record information in a medium at the optimum power, by checking the medium characteristics and laser diode (LD) characteristics and correcting a variation in optical power. OPC is a record power control method by which test data undergoes trial write in a power calibration area (PCA) at the innermost circumference of an optical disk by stepwise changing a record power of an LD and at a predetermined record velocity (linear velocity), and β of signals reproduced from the recorded test data are evaluated to determine the record power with the best β as the optimum record power at that record velocity. Generally, the optimum record power changes with the record velocity, and the characteristics of an optimum record power relative to a record velocity of each medium are prepared.
JP-A-5-225570 discloses a method of obtaining the characteristics of an optimum record power relative to a record velocity by determining two optimum record powers by performing OPC at two different record velocities and executing an interpolation or extrapolation process of the two optimum record powers.
The record velocity-optimum record power characteristics by OPC are obtained by optimum record powers at predetermined record velocities. These characteristics do not contain the information of whether an error occurs if new data is written thereafter at some record velocity and the information of the fastest recordable velocity.
Requirements of recording data in an optical disc at as high a velocity as possible are becoming high in order to shorten a record time of an optical disc which can be recorded at a high velocity. Some optical discs have packages labeled as 8×, 16× or the like. This label may be used as a criterion for determining the fastest recordable velocity. The velocity written on this label has usually some margin by considering a warp of an optical disk, pigment variation and the like. Data can be written in some media at a velocity faster than the fastest recordable velocity written on the label. CD-R does not provide information of the fastest recordable velocity. Some media do not support recording at a low velocity (1×) or at a high velocity (8× or higher). In such cases, if only the record velocity-optimum record power characteristics by OPC are relied, write-once and reproduction may become impossible because of a low quality of recorded data.
In a so-called partial CAV record, data is recorded from the inner circumference of an optical disc under constant angular velocity (CAV) control, and after the velocity reaches the fastest recordable velocity, data is recorded up to the outermost circumference under constant linear velocity (CLV) control. It is important for the partial CAV record to determine a proper fastest recordable velocity in order to shorten the record time. The fastest velocity of CAV record is not necessarily equal to or faster than a CLV enabled velocity in the inner circumference. It is difficult to determine a correct fastest recordable velocity by using only conventional OPC.